The present invention relates to gas burning lanterns. In particular, the present invention relates to a gas burning lantern with an improved regulator and an improved choke.
A conventional gas burning lantern typically comprises a refillable fuel storage tank, fuel delivery apparatus, and a burner attached to the fuel delivery apparatus. The fuel delivery apparatus may include a regulator and other equipment, such as a operator gas flow controller. The burner typically comprises a mantle which, when ignited with a fuel/air mixture provided by the fuel delivery apparatus, emits a bright light. The mantle in such a lantern contains a catalyst, such as yttrium-oxide, which converts the heat from the flame into light. The burner is covered by a transparent glass globe. Fuel typically used with such lanterns includes liquid propane or butane.
The regulator in such a lantern accepts gas from a gas source and provides a steady, controlled gas stream as an output. The regulator or another mechanism mixes air with the gas flow to produce an air/gas mixture. Typically a valve allowing gas to flow through the regulator is closed or narrowed as gas pushes against a diaphragm assembly in the regulator. The narrowing of the valve lowers the gas flow through the regulator, lowering the pressure on the diaphragm and thus allowing the valve to open somewhat. Quickly an equilibrium is established where the diaphragm accepts a certain amount of gas pressure and in turn allows the valve to open a certain amount. A regulator may have a control mechanism allowing a user to stop the flow of gas through the regulator in order to turn the lantern on or off. Such mechanisms engage the diaphragm assembly or another portion of the regulator to open or close the valve in the regulator.
A typical regulator allows gas to enter through a passage and then to leave the regulator through a passage which is more or less at a 90 degree angle from the entry passage. Thus, typically, gas does not exit the regulator travelling in the same direction as which it entered (for example, entering the regulator through the bottom and leaving through the top), as the diaphragm assembly provides a barrier around which gas cannot flow. To allow for a better arrangement of components, it is desirable to have gas exit the regulator in the same direction which it entered.
Some regulator designs allow gas to flow straight through the regulator, in the same direction which the gas enters, by including a tube or opening through the regulator assembly. Gas then may flow up through the regulator. However, such regulators either lack control mechanisms allowing the user to regulate the flow of gas or include awkward control mechanisms. For example, an arm may connect to the diaphragm assembly to allow a user to turn the flow of gas on or off. The arm extends out of the regulator and out of the lantern, and swings in a semi-circle as it is turned around the side of the lantern. Such a design has a large profile and is awkward, as the swing of the arm takes up too much space. Other designs have control mechanisms separate from a diaphragm assembly or separate from a regulator. Such extra equipment adds to the complexity and expense of the lantern.
The mantle in a typical lantern is most efficient at producing light when operating at relatively high temperatures. The lantern flame burns hotter with leaner air/gas mixtures; i.e., with higher air/gas ratios. However, leaner gas mixtures are harder to light, particularly when a lantern is cold, and particularly if an automatic lighting mechanism is used rather than an open flame from a match. A richer air/gas mixture allows for easier lighting, but is less efficient.
The air/fuel mixture may actually get richer after the lantern heats up. The amount of gas flowing from the lantern""s gas tank to the mantle typically remains constant over various operating conditions. However, the amount of air entering the system to mix with the gas is affected by the pressure in the system. A flame operating in a hot lantern may cause back pressure through the system, lowering the amount of air entering the lantern and creating a richer mixture.
Current designs attempt to solve the problem of providing a lantern which is both efficient and easy to light in various manners. Certain lanterns set the air/gas mixture at an intermediate level which allows relatively easy lighting but which also allows for reasonable efficiency. Such a solution is imperfect, as the lantern is neither optimally efficient nor optimally easy to light. Other lanterns include a user operated choke which allows a user to alter the air/gas mixture so that it is rich on lighting and lean during operation. Such a solution is imperfect, in that it requires extra equipment and user operation. The extra equipment adds expense and eventually may wear out.
It would be desirable to have a regulator which allows gas to exit the regulator in the same direction which it enters (e.g., through the top of the regulator) and in addition which has a simple, easy to use, low profile, low cost, integral mechanism for allowing a user to control the flow of gas through the regulator. It would be desirable to have an automatic choke in a gas lantern which is simple and reliable.
The gas operated lantern of the present invention includes a regulator having a simple mechanism allowing a user to start or stop the flow of gas through the regulator. The regulator controls the flow of gas through the lantern, and preferably exhausts an air/gas mixture out of the regulator in the same direction as which gas enters the regulator. The regulator includes a diaphragm assembly which presses down on a valve assembly to open the valve assembly. A stem enters the regulator and is turnable by the user to raise the diaphragm assembly and thus cause the valve assembly to close. Such a method of allowing the user to control the flow of gas through the regulator is simple, less awkward and less expensive than existing designs.
The lantern also includes an automatic choke which is reliable, will not wear out, and which is simple and inexpensive. The choke is preferably a strip of metal located in the burner tube of the lantern which acts to close off a portion of the burner tube when the lantern is cold, causing the air/fuel mixture to become richer and thus easier to light. As the lantern heats up, the choke straightens to open the burner tube, allowing a greater flow of air through the lantern and causing the air/fuel mixture to become leaner and thus raising the efficiency of the lantern.